Scenario 1: The Ariane 6 family proofs adequate for the demand of ESA and sat operators for the next 20 - 30 years.

In this case only an evolution would be required. Under consideration: Ariane 6.6 (6 SRB, 13 tons to GTO) to meet increasing satellite masses combined with (or instead of): 1a) an replacement of Vulcain 2.1 with Prométhée, 2b) an upgraded version of th Vinci upper stage engine.

Scenario 2: The market for mega constellations takes off, a Soyuz-like launch cadence of 50 launches per year is required.

This isn't considered achievable with Ariane 6, the answer would be an all new launcher with that lists several of the buzzwords I already mentioned in my earlier post (launcher least partially re-usable, upper stage re-use (3 to 5 round trips) achieved with re-fuelling in orbit, high-cadence production that is flexible if the market contracts).

I deem senario 1: Drop-in replacement of Promethee instead of Vulcan 2.1 very unlikely. A Ariane Next that uses a promethee engine would always be a completely new/different launcher. LOx-LH has a density of 0.28-0.32 mT/M3 (kg/L); LOx-LNG (LCH4) is 0,82-0,83 mT/M3. So the fuel mass in the Core stage would nearly triple. So one Prometheus would not suffice.A Vulcain 2.2 or 2.3 (2.2 is already planned if I'm not mistaken) would be a much more logical drop in replacement. Vulcain 2.2 has 3D printed Turbopumps if I'm not mistaken. A new injector design (additive manufactured) and ignition system would lower the cost of a Vulcain engine a lot. I think that's a beter alternative than Scenario 1.

I deem senario 1: Drop-in replacement of Promethee instead of Vulcan 2.1 very unlikely. A Ariane Next that uses a promethee engine would always be a completely new/different launcher. LOx-LH has a density of 0.28-0.32 mT/M3 (kg/L); LOx-LNG (LCH4) is 0,82-0,83 mT/M3. So the fuel mass in the Core stage would nearly triple. So one Prometheus would not suffice.A Vulcain 2.2 or 2.3 (2.2 is already planned if I'm not mistaken) would be a much more logical drop in replacement. Vulcain 2.2 has 3D printed Turbopumps if I'm not mistaken. A new injector design (additive manufactured) and ignition system would lower the cost of a Vulcain engine a lot. I think that's a beter alternative than Scenario 1.

Vulcan 2.2 will be phased in first and Vulcan 2.3, which will be nearly completely 3D printed, will follow later both on Ariane-6 in the future.

A six SRB Ariane 6 with upgraded Vulcain and Vinci engines could probably do manned Lunar missions with twinned launches! One for the Spacecraft and one for the Departure Stage. Roll on, the ESA 'Space Village'!

Logged

"Those who can't, Blog". 'Space Cadets' of the World - Let us UNITE!!(crickets chirping)

5th DLR Industrial Days at the Lampoldshausen siteThe future of space transport: Will large satellite networks change our way into space?

Excerpt concerning Prometheus:

The road to Ariane 6 and beyond

Competitive and reliable, high-performance and flexible – these adjectives best describe the Ariane launcher family that will now be expanded accordingly with the addition of Ariane 6. Airbus Safran Launchers, prime industrial contractor for the Ariane 6 programme, has now reached the key milestones: firstly, technical maturity of the launcher system has been confirmed, and secondly, the European Space Agency (ESA) has now signed an addendum to the original Ariane 6 contract, releasing the necessary funds to complete development and industrialisation. The reduction in actual costs for launching without restricting the launcher's reliability is of particular significance in this respect. Moreover, performance and cost-efficiency of Ariane 5 will be further improved as a means of prevailing in an increasingly competitive market. Starting in 2023, Ariane 6 is scheduled to launch up to 12 times per year and replace the current Ariane 5 system.

The main actors within the European aerospace sector have their eyes firmly fixed on the commissioning of Ariane 6. Moreover, Europe is already actively preparing a future launcher system: the French space agency (CNES), Airbus Safran Launchers and DLR are collaborating within the Prometheus Project to develop a cost-efficient, high-thrust and reusable rocket engine powered by liquid oxygen (LOX) and methane. Numerous projects around the world have investigated the use of methane as a rocket fuel for decades. But so far the LOX/methane propulsion system has not been used in any real launcher. Since the 2016 ESA Council at Ministerial Level, the committee that oversees European space policies, however, the research and technology development of the Prometheus project have been included in the ESA Future Launchers Preparatory Programme (FLPP).

Research for the adoption of new technologies

A fuel combination comprising methane and liquid oxygen has an auspicious role to play in the development of new liquid rocket fuels for space. The potential options of methane extend from adding it to the current liquid fuel engines used in the Ariane launchers, to a complete replacement of liquid hydrogen. DLR engineers in the Prometheus project are now working on developing the LOX/methane technology as quickly as possible for use within the European space programme. The targets are clearly defined: Airbus Safran Launchers and the DLR Institute of Space Propulsion entered into an alliance in 2016 to drive rapid progress in LOX/methane technology. While the engineers at Airbus Safran Launchers designed and built a promising technology demonstrator, the DLR engineers adapted the P3 test rig to suit these entirely new conditions, especially with regards to the fuel supply. The project partners then conducted a 12-month test campaign that yielded important findings for the continued development of necessary, critical technologies such as the combustion chamber. "Our test campaign has paved the way for the development of innovative LOX/methane technology," explained Gerald Hagemann, Head of Liquid Propulsion Engineering at Airbus Safran Launchers. Upon completion of a test campaign with Vulcain 2.1 – the main stage engine of the Ariane 6 rocket – the aim is to run tests on a LOX/methane technology demonstrator with 100 tons of thrust under representative conditions on the P5 test rig at the DLR Test Centre for Rocket Propulsion Systems in Lampoldshausen. This LOX/methane engine has the potential to reduce the costs of the Vulcain main stage propulsion system, developed by Europe in the 1980s, by a factor of 10.

• A launcher for "beyond 2030".• At the moment a team of 15 is working on the concept.• Further cost reduction by a factor of 2, compared to Ariane 6.• Tailored to both Commercial and State customers.• Development time reduced from 10 to 5 years.• Adaptable industrial base: o Ability to increase production if demand requires it... o But able to scale down and stay profitable if the commercial market shrinks.• The designated engine is Prométhéus o 10x cheaper to manufacture (compared to Vulcan 2) o 50% production time o Extensive use of additive manfivuating aka 3D-printing o Methane instead of LH2 propellant, easier to handle, yet similarities should speed up development. o One possible scenario is to use Prométhéus for both 1st and 2nd stage.• Callisto will be the prototype for reusability o Re-ignition at high altitude studied by Onera• Possibility of 2nd stage reuse is being considered.• Upper Stage could remain in orbit and conduct several GTO missions

It's discouraging that for "beyond 2030" the plans are less ambitious than what SpaceX has right now and what Blue Origin is working on and targeting for more than a decade earlier than 2030.

And while only 15 people are working on this plan that doesn't even match SpaceX today, Europe is charging full speed ahead with A6, which is even more hopelessly behind.

Looks like the Europeans are getting more serious about reusable rocketry (and costs):

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Europe Sets Sights on Cheap Rocket Engine by 2030s

Quote

PARIS (Reuters) - Europe aims to develop a low-cost, reusable rocket engine for use after 2030 under a deal between Airbus Safran Launchers and the European Space Agency (ESA).

They signed a development contract at the Paris Airshow on Thursday to develop a demonstrator engine, powered by liquid oxygen and methane.

Airbus Safran said it would use new manufacturing techniques, including the use of 3D printers, to keep the engine's cost down to around 1 million euros ($1.1 million).

"The commercial market - at least the European one - is asking for reliability, on-time delivery and cost, and we have to find the best way to answer these market expectations," its CEO, Alain Charmeau, told Reuters.

The firm, a joint venture between Airbus and Safran that will become ArianeGroup on July 1, currently powers the rockets it uses to launch satellites for commercial clients with Vulcain 2 engines costing around 10 million euros each.

But not all in on reusable rockets yet...

Quote

"We need, and will have Ariane 6 in 2020, but we also have to prepare for the future ...and that is why this (Prometheus) program is important," he said.

The jury was still out on the issue of reusability, however.

California-based Space Exploration Technologies (SpaceX) earlier this year achieved what it called "a huge revolution in spaceflight" by reusing part of one of its Falcon 9 rocket on a subsequent launch.

Charmeau said Prometheus would include work on reusability. "(But) the market is not asking for reusability... As long as we have a limited number of institutional launches it's difficult to bet on reusability."

Without right engine, ArianeGroup can't even consider a RLV. This engine is step in right direction. In short term replace Vulcain with 1 or 2 of these engines. With switch to methane the same size stage could probably support 2 engines giving A6 a performance increase. Maybe add flyback engine pod.

A smaller booster (no SRBs) using same flyback engine pod could replace Vega.

Without right engine, ArianeGroup can't even consider a RLV. This engine is step in right direction. In short term replace Vulcain with 1 or 2 of these engines. With switch to methane the same size stage could probably support 2 engines giving A6 a performance increase. Maybe add flyback engine pod.

A smaller booster (no SRBs) using same flyback engine pod could replace Vega.

The MT Aerospace proposal for Ariane 6 was an all liquid modular design, but was struck down because it endangered the solid propulsion industry.

ArianeGroup signs a first contract with ESA to develop the future Prometheus engine

• Airbus Safran Launchers, which will become ArianeGroup on July 1, 2017, today signed a first contract at the Paris Air Show with the European Space Agency (ESA) to develop the Prometheus demonstrator• Prometheus is a low - cost reusable engine demonstrator running on liquid oxygen (LOx) and methane • Its applications are designed to equip European launchers as of 2030

I've written this here already at least 3x. The current situation for European launchers was created during the 2012 ministerial. CNES (France) wanted Ariane 6, DLR (Germany) wanted Ariane 5ME. They compromised and decided to start A5ME upper-stage development and further design studies for Ariane 6. But for most Ariane 6 configurations a new liquid first stage was required. This was a proposal for the Future Launcher Preparations Program FLPP3 called High Thrust Engine (HTE) demonstrator. Unfortunately the HTE program wasn't backed, and didn't proceed. Thus for the A6-studies they were stuck to current engine technology. I think the current A6 is much closer to A5ME then to what CNES envisioned with Ariane6 in 2012.Most likely most of the expenses of the Ariane 6 program go into new factories. The factories are able to be reconfigured for future Ariane Launchers. The other part of A6 is change of responsibility and implementation of the mature technologies that would also have been integrated into A5ME.

Back to Callisto. I expect it will use much smaller engines than Romeo or Prometheus. Most likely in the 25-100kN range. The results of both the Callisto and Prometheus developments could lead to a reusable A7, which would be an up-scaled Callisto. But I think A multi segment P280 or P420 (2 or 3 P140 segments) could also be a good alternative for a reusable multi engine first stage. In case reuse doesn't work. So P280 - Prometheus or P420 - Prometheus.Another possibility is replacing the Ariane 6 core with a 3.4m diameter one prometheus engine core.(This could be in line with what I wrote in the Vega Update topic #207)

But I think introducing more additive manufacturing in the Vulcan 2 and Vince production proces, will be the first further evaluation of Ariane 6. (Aka Vulcan 2.2 and 2.3)I don't see any down side to the Prometheus engine development program. It will bring a lot of new launcher configurations. Vega L could maintain the solid stage production capability. (Though Callisto could compete with it)